Hi @hao.bui
Welcome to the Auth0 Community!
If you are using Auth0 Lock and you are redirecting from your React application to the Auth0 Lock, then by enabling the MFA in the dashboard, users should be automatically asked to enroll and prompted to use it whenever they log in. Please note that the redirect mode is the default for Auth0 Lock.
However, if you are using Popup mode, MFA will not be supported as mentioned in our documentation.
If you have any other questions, feel free to leave a reply!
Kind Regards,
Nik